To facilitate the understanding of the present invention it may be convenient to first illustrate the nature and character of whole blood. This should however not constitute a limitation of the present invention, but should rather be taken as a convenient instrument to understand the present invention when used in one of its more special fields of use.
Whole blood is a tissue consisting of cells suspended in plasma. Said cells constitute about 45% by volume, while the remaining 55% constitutes plasma. Said suspended blood cells comprise inter alia red cells, white cells and thrombocytes. By means of the present device it is possible not only to separate cells from plasma, but also to separate said several cells from each other into separate cell fractions (so-called cytapheresis) if desired. Said separate fractions of said whole blood may be used independently for different purposes. For example said white cells are of particular concern for blood research, immunological studies and for clinical use in transplantations of organs. Furthermore, said white cells may be used for support therapy by cancer patients, the white cells of which in one or another respect have been destroyed through different anti-cancer drugs.
The red cells as well as the plasma are of particular concern for transfusion purposes.
Known devices for the separation of whole blood into different components have under favorable conditions provided a sufficient separation, but have, on the other hand, had drawbacks sometimes entailing fatal consequences for said whole blood and said separated components. The main reason has been the rotating coupling which normally is used to connect the transferring element to the rotating separation unit. Through the heat of friction which is created in rotating couplings in the contact surface between a stationary and a rotating element, said whole blood has been exposed to large temperature increases during its passage into the separation chamber. This is also true for the separated blood fractions when said fractions have passed the rotating coupling during egress from said separation unit. Even though said problem to some extent has been solved by cooling said rotating coupling with a cooling fluid, it still remains as being not completely solved.
Another drawback by said known devices, which use rotating couplings, is that blood cells may be damaged due to shear-stresses at the contact area between surfaces moving relative to each other.
The object of the present invention is therefore to provide a device of the above-mentioned kind, i.e. a device which is similar to said known devices for the separation of whole blood into fractions having different densities, which uses a rotating separation unit comprising a separation chamber, and a transferring element in fluid communication with said chamber. The present device, on the contrary, does not use rotating couplings to connect the separation unit to the transferring element.